This invention relates generally to fuel filter systems for internal combustion engines. More particularly, this invention relates to a base assembly for a fuel filter system which employs a replaceable cartridge mountable to the base.
In fuel filter systems to which the invention relates, such as disclosed in U.S. Pat. Nos. 5,203,994, 5,302,284 and 5,766,463, a disposable filter cartridge is mounted to a base in such a way that it can be relatively easily removed at pre-established intervals for replacement purposes. The base typically has a pair of coaxial central conduits which provide the fuel inlet and outlet to the filter cartridge. The cartridge may contain a single or multiple stage filter configuration for filtering the fuel. In numerous embodiments the replaceable filter cartridge is suspended below the base, but other orientations are commonly employed. The base is mounted to the vehicle in any of a number of locations depending on the particular application and spacial constraints. The base typically also includes inlet and outlet connectors which may be in the form of posts or other structures which mount fittings and connect with the input and output lines to the base.
In one well known conventional construction, a retainer ring is threaded to the base and engages a circumferential roll seam shoulder of the filter cartridge to retain the cartridge to the base. The retainer ring may alternately include a ramp-like structure which mates with a complementary ramp of the base and the cartridge and/or retainer ring is spring-loaded to facilitate retention of the cartridge to the base. The cartridge typically includes sealing grommets or other sealing structures to seal the cartridge with the inlet and outlet conduits of the base. It should be appreciated that the base structures for replaceable filter cartridges may assume a wide variety of configurations and spacial orientations.
Briefly stated, the invention in a preferred form is a novel base module for a filter assembly, such as a fuel filter assembly. The base module may be a molded member that may, for example, be formed from plastic, glass-filled nylon or other similar materials. The module comprises a header portion having a central axis and defining a generally cylindrical receiving cavity symmetrical about the axis. A retainer integrally extends from the header portion and includes an inward retaining channel generally coaxial with the axis.
The retaining channel is defined by a shoulder, side wall and retaining lip. The retaining lip is adjacent the open end of the receiving cavity and includes a plurality of angularly spaced axial slots. The axial slots are configured to receive tabs that radially extend from the peripheral roll seam of a filter cartridge. The shoulder, side wall and retainer lip provide a retaining structure wherein a cartridge is mountable to the base module by axially inserting the tabs through the axial slots and rotating the cartridge. The retaining structure and tabs are configured to provide enhanced frictional engagement between the tabs and the retaining channel.
In a particular aspect of the invention, the side wall has a plurality of ramp-like projections extending radially inward from a position adjacent one of the axial slots. As the cartridge and its associated tabs are rotated in the retaining structure, the ramp-like projections engage the radially outer surface of the tabs. The retainer lip may include a plurality of inclined portions extending from each axial slot to a pinch crest. The inclined portions engage the underside of each tab during rotation of the cartridge and force the cartridge axially into the receiving cavity. The pinch crests frictionally engage the tabs against the axially opposed shoulder.
In an alternative embodiment, the retaining structure may include a stamped metal split ring that is held in a generally fixed rotational and axial relationship within the retaining channel, essentially replacing the retainer lip. The split ring may define the axial slots and include a bump or detent associated with each axial slot. The tabs of a received cartridge pass through the axial slots and over the bumps upon rotation. The bumps provide enhanced frictional engagement between the tabs and the split ring to prevent the tabs from easily reversing direction and unintentionally falling out of the axial slots.
In another aspect, the header portion of the base module provides inlet and outlet conduits extending axially into the receiving cavity and associated inlet and outlet connectors in communication with the respective conduits. A bracket may integrally extend from the header portion for mounting the base module to a mounting structure of the vehicle. The bracket preferably includes at least one opening for receiving a mounting fastener. In one described embodiment, the first and second conduits are coaxial, and the connectors extend generally axially.
In a further aspect, a disposable filter cartridge having radially protruding retention tabs may be received in the receiving cavity wherein the tabs are captured in the retaining channel. The tabs preferably complement the ramp-like projections of the retainer.
An object of the invention is to provide a new and improved base module for a fuel filter system.
Another object of the invention is to provide a new and improved base module adapted for securely receiving a filter cartridge and having an efficient and low cost construction.
A further object of the invention is to provide a new and improved base module that has a substantially molded construction.
A yet further object of the invention is to provide a filter cartridge and base module assembly in which the cartridge can be installed and securely retained without the use of tools or separate retaining parts.
Other objects and advantages of the invention will become apparent from the specification and the drawings.